The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization. Founded in 1911, the organization focuses on coordinating, analyzing, publishing, and archiving variable star observations made largely by amateur astronomers. [1] The AAVSO creates records that establish light curves depicting the variation in brightness of a star over time. The AAVSO makes these records available to professional astronomers, researchers, and educators.
Professional astronomers do not have the resources to monitor every variable star. Hence, astronomy is one of the few sciences where amateurs can make significant contributions to research. [2] In 2011, the 100th year of the AAVSO's existence, the twenty-millionth variable star observation was received into their database. [3] The AAVSO International Database (AID) has stored over thirty-five million observations as of 2019. [4] The organization receives nearly 1,000,000 observations annually from an estimated amount of 2,000 professional and amateur observers, and is quoted regularly in scientific journals. [5] [6] [7] The International Variable Star Index (VSX) website, maintained by the AAVSO, is cataloging (as of November 2023) 2,277,999 variable stars. [8]
The AAVSO is also very active in education and public outreach. They routinely hold training workshops for citizen science and publish papers with amateurs as co-authors. In the 1990s, the AAVSO developed the Hands-On Astrophysics curriculum, now known as Variable Star Astronomy [9] (with support from the National Science Foundation [NSF]). In 2009, the AAVSO was awarded a three-year $800,000 grant from the NSF to run Citizen Sky, [10] a pro-am collaboration project examining the 2009-2011 eclipse of the star epsilon Aurigae. [11]
The AAVSO headquarters was originally located at the residence of its founder William T. Olcott in Norwich, Connecticut.
Minor Planet (8900) AAVSO is named after the organization. [12]
After AAVSO's incorporation in 1918, it unofficially moved to Harvard College Observatory, which later served as the official AAVSO headquarters (1931–1953). [13] Thereafter, it moved around Cambridge before their first building was purchased in 1985 - The Clinton B. Ford Astronomical Data and Research Center. [14] In 2007, the AAVSO purchased and moved into the recently vacated premises of Sky & Telescope magazine. [15]
As of September 16, 2022, the Executive Director of the AAVSO is Brian Kloppenborg. Before he assumed this role, Kathy Spirer worked in this capacity for nine months, following the resignation of Styliani ("Stella") Kafka -who was in charge from February 2015 till the ember months of 2021. She succeeded Arne Henden. The previous director of the AAVSO for many decades was Janet Mattei, who died in March 2004 of leukemia. [16]
The AAVSO currently has over 2,000 members and observers, with approximately half of them from outside the United States. This list only consists of those with Wikipedia pages.
Serpens is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput to the west and Serpens Cauda to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer". In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda.
Circinus is a small, faint constellation in the southern sky, first defined in 1756 by the French astronomer Nicolas-Louis de Lacaille. Its name is Latin for compass, referring to the drafting tool used for drawing circles. Its brightest star is Alpha Circini, with an apparent magnitude of 3.19. Slightly variable, it is the brightest rapidly oscillating Ap star in the night sky. AX Circini is a Cepheid variable visible with the unaided eye, and BX Circini is a faint star thought to have been formed from the merger of two white dwarfs. Two sun-like stars have planetary systems: HD 134060 has two small planets, and HD 129445 has a Jupiter-like planet. Supernova SN 185 appeared in Circinus in 185 AD and was recorded by Chinese observers. Two novae have been observed more recently, in the 20th century.
R Leporis (R Lep), sometimes called Hind's Crimson Star, is a well-known variable star in the constellation Lepus, near its border with Eridanus. It is designated "R" in the chart to the right.
Janet Akyüz Mattei was a Turkish-American astronomer who was the director of the American Association of Variable Star Observers (AAVSO) from 1973 to 2004.
Ellen Dorrit Hoffleit was an American senior research astronomer at Yale University. She is best known for her work in variable stars, astrometry, spectroscopy, meteors, and the Bright Star Catalog. She is also known for her mentorship of many young women and generations of astronomers.
Clinton Banker Ford was an American investor, musician and amateur astronomer specializing in the observation of variable stars.
Carolyn Hurless was an American astronomer and an American Association of Variable Star Observers merit award winner. She made an estimated 78,876 astronomical observations in her lifetime.
Epsilon Aurigae is a multiple star system in the northern constellation of Auriga, the charioteer. It is an unusual eclipsing binary system comprising an F0 supergiant and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two small B-type stars. The distance to the system is still a subject of debate, but data from the Gaia spacecraft puts its distance at around 1,350±300 light years from Earth.
Margaret Walton Mayall was an American astronomer. She was the director of the American Association of Variable Star Observers (AAVSO) from 1949 to 1973.
Paula Szkody is a professor in the Department of Astronomy at the University of Washington in Seattle. She served as president of the American Astronomical Society from 2020 to 2022.
Michiel Daniel Overbeek, also known as Danie Overbeek, was a South African amateur astronomer and one of the most prolific variable star observers.
Edward A. Halbach was an American amateur astronomer and prolific variable star observer.
R Canum Venaticorum is a Mira variable star in the constellation Canes Venatici. It ranges between magnitudes 6.5 and 12.9 over a period of approximately 329 days.
S Coronae Borealis is a Mira variable star in the constellation Corona Borealis. Its apparent magnitude varies between 5.3 and 13.6, with a period of 360 days—just under a year. Within the constellation, it lies to the west of Theta Coronae Borealis, and around 1 degree southeast of the eclipsing binary star U Coronae Borealis.
R Boötis is a variable star in the northern constellation of Boötes. Typically the star is too faint to be readily visible to the naked eye, with a brightness that fluctuates between apparent visual magnitudes of 9.98. The distance to this star is approximately 2,150 light years based on parallax measurements. It is drifting closer with a radial velocity of about −58 km/s.
Lambda Eridani is a star in the constellation Eridanus. It is visible to the naked eye on a dark night with an apparent visual magnitude of 4.27. The distance to this star, based upon an annual parallax shift of 0.00402 arcseconds, is roughly 810 light years.
S Boötis is a Mira variable in the constellation Boötes. It ranges between magnitudes 7.8 and 13.8 over a period of approximately 270 days. It is too faint to be seen with the naked eye, however when it is near maximum brightness it can be seen with binoculars.
U Microscopii is a Mira variable star in the constellation Microscopium. It ranges from magnitude 7 to 14.4 over a period of 334 days. The Astronomical Society of Southern Africa in 2003 reported that observations of U Microscopii were very urgently needed as data on its light curve was incomplete.
YZ Reticuli, also known as Nova Reticuli 2020 was a naked eye nova in the constellation Reticulum discovered on July 15, 2020. Previously it was known as a VY Sculptoris type object with the designation MGAB-V207.